The present disclosure relates to an acoustic apparatus, an acoustic adjustment method and a program, in particular, to an acoustic apparatus and the like adjusting acoustic characteristics of a plurality of speakers configuring a multichannel reproduction system.
In the related art, a multichannel reproduction system handling a multichannel sound signal such as a 5.1 channel signal or the like has hitherto been common. In order to accurately realize a surround effect using the multichannel sound signal, examples of the necessary conditions are that the distances to each of the front speaker, the center speaker, and the surround speakers from the listening position are all equal, that all the speakers are the same, and that the same amplitude characteristics and phase characteristics are provided.
However, in a reproduction environment in a typical home, it is often the case that the above-mentioned conditions are not satisfied due to the physical limitations of the room, the speakers, and the like. In such a case, in order to accurately realize the surround effect, it is important to appropriately adjust the acoustic characteristics of the sound signal output from each speaker.
In the related art, there has been an acoustic apparatus provided with an automatic acoustic characteristic adjustment function which is capable of automatically adjusting the acoustic characteristics of the audio signals output from each speaker. Such an apparatus outputs a test signal such as noise or an impulse signal to each speaker in advance, picks up a response signal from each speaker using a microphone placed in a listening position, and performs recording. Then, each recorded signal is analyzed, an impulse response is obtained, and the time taken to arrive at the listening position from each speaker, as well as the amplitude characteristics and phase characteristics of each speaker are calculated. Further, a delay amount and a filter coefficient for compensating for the difference in the arrival time during the response signal period from each speaker, the difference in the amplitude characteristic, and the difference in the phase characteristic are calculated.
During sound signal reproduction, the acoustic apparatus applies a delay process and a filter process to the output signal to each speaker and outputs an optimal signal to each speaker based on the above-mentioned calculated result. The number of channels to which the delay process and filter process are applied is basically 5 channels except for dedicated low-pass channels; however, the number of channels may be 7 channels, 9 channels or more.
In the acoustic apparatus of Japanese Unexamined Patent Application Publication No. 07-184293, description is given of performing compensation of the speaker output during reverse phase connection. That is, the acoustic apparatus outputs a test signal of a pulse waveform to each speaker and picks up a response signal from each speaker using a mike. Here, determination of the polarity is performed by comparing the reference signs of the values of the waveform peaks of the test signal and the response signal, and it is judged that when the reference signs are the same, the connection of the speaker is in-phase, and when the reference signs are different, the connection of the speaker is reverse phase. Here, in the case of reverse phase connection, compensation of the speaker output during reverse phase connection is performed by reversing the polarity of the signal to be supplied to the speakers.